(1) Field of the Invention
The present invention relates to isolation mounts and in particular, to an isolation mount for mounting an acoustic projector or transducer to a hull structure of an underwater vehicle.
(2) Description of the Prior Art
Acoustic projectors are commonly used in underwater vehicles to generate sound which propagates through the water, for example, as part of an underwater vehicle guidance system. In the past, acoustic projectors 10, FIG. 1, have been mounted directly in the wall 12 of the cylindrical hull 14 of the underwater vehicle. Typically, the hull 14 includes a cavity or aperture 16 cut through the wall 12. The acoustic projector 10 is received through the cavity 16 and is fastened to the hull with bolts 18 such that the projector 10 forms a flush contour with the hull 14. An `O` ring seal 19 typically provides a water tight seal between the acoustic projector 10 and the wall 12 of the hull 14. Similarly, transducers used to detect and measure energy, such as acoustic energy, are also mounted directly to the hull 14 of an underwater vehicle.
An acoustic projector 10 is generally designed to have certain characteristics with respect to frequency response and range of operation. The way in which the acoustic projectors are mounted directly to the underwater vehicle hull adversely interferes with the operation of the acoustic projector. When sound is generated by the acoustic projector, energy from the projector is coupled into or transmitted to the hull structure, resulting in resonances and interference with the sound being propagated into the water. The frequency response of the acoustic projector is thereby degraded and will adversely affect the guidance system or other system in which the acoustic projector is used. Vibrations and acoustic energy generated by or transmitted through the hull structure to the projector can also interfere with operation of the projector.
Some attempts have been made to mechanically and acoustically isolate noise generating devices and transducers from a support structure. Existing isolation mounts, however, are not capable of being retrofitted with existing mounting arrangements without physically modifying the hull structure and/or the projector. Existing isolation mounts also do not provide the water tight seal that may be necessary when mounting acoustic projectors or other devices to the hull of an underwater vehicle.